METHOD FOR THE REMOVAL OF HEAT STABLE AMINE SALTS FROM AN AMINE ABSORBENT
The proposed invention relates to a method and a system for the removal of heat stable amine salts from an amine absorbent used in a carbon dioxide (CO 2 ) capture process, the method comprising: withdrawing amine absorbent containing heat stable amine salts from the CO 2 capture process; subjecting the withdrawn amine absorbent containing heat stable amine salts to a residual CO 2 removal step; subjecting the amine absorbent from the residual CO 2 removal step to a separation step to separate heat stable amine salts from the amine absorbent; and returning the amine absorbent having a reduced concentration of heat stable amine salts to the CO 2 capture process.
1 . A method for the removal of heat stable amine salts from an amine absorbent used in a carbon dioxide (CO 2 ) capture process, comprising:
withdrawing amine absorbent containing heat stable amine salts from the CO 2 capture process;
subjecting the withdrawn amine absorbent containing heat stable amine salts to a residual CO 2 removal step;
subjecting the amine absorbent from the residual CO 2 removal step to a separation step to separate heat stable amine salts from the amine absorbent; and
returning the amine absorbent having a reduced concentration of heat stable amine salts to the CO 2 capture process.
2 . A method according to claim 1 , wherein the residual CO 2 removal step comprises removing residual CO 2 from withdrawn amine absorbent by a method selected from the group consisting of stripping CO 2 , flashing CO 2 and combinations thereof.
3 . A method according to claim 2 , wherein the residual CO 2 removal step comprises stripping the withdrawn amine absorbent to remove residual CO 2 .
4 . A method according to claim 2 , wherein the residual CO 2 removal step comprises flashing the withdrawn amine absorbent to remove residual CO 2 .
5 . A method according to claim 2 , wherein the residual CO 2 removal step comprises stripping and then flashing the withdrawn amine absorbent to remove residual CO 2 .
6 . A method according to claim 2 , wherein the flashing is performed under near vacuum conditions.
7 . A method according to claim 1 , wherein the CO 2 capture process comprises:
scrubbing a gas stream comprising CO 2 with an amine absorbent such that a CO 2 rich amine absorbent is formed;
regenerating the CO 2 rich amine absorbent by heating it to separate CO 2 from the amine absorbent, such that a CO 2 lean amine absorbent is formed; and
recycling regenerated CO 2 lean amine absorbent to the scrubbing step.
8 . A method according to claim 7 , wherein the withdrawn amine absorbent containing heat stable amine salts is regenerated CO 2 lean amine absorbent.
9 . A method according to claim 8 , wherein the regenerated CO 2 lean amine absorbent has a temperature of at least 100° C., such as at least 120° C.
10 . A method according to claim 1 , wherein the separation step comprises subjecting the amine absorbent from the residual CO 2 removal step to electrodialysis and/or ion exchange.
11 . A method according to claim 10 , wherein the separation step comprises subjecting the amine absorbent from the residual CO 2 removal step to electrodialysis.
12 . A method according to claim 10 , wherein the separation step comprises subjecting the amine absorbent from the residual CO 2 removal step to ion exchange.
13 . A method according to claim 1 , further comprising cooling the amine absorbent from the residual CO 2 removal step before subjecting it to the separation step.
14 . A method according to claim 13 , further comprising subjecting the amine absorbent from the residual CO 2 removal step to indirect heat exchange with the amine absorbent coming from the separation step.
15 . A carbon dioxide (CO 2 ) capture system using an amine absorbent for absorption of CO 2 from a gas stream, having a subsystem for the removal of heat stable amine salts from an amine absorbent, said subsystem comprising:
a residual CO 2 removal unit in liquid connection with, and configured to receive, an amine absorbent stream containing heat stable amine salts from the CO 2 capture system, and operative for separating residual CO 2 from said amine absorbent stream; and
an amine reclaimer in liquid connection with, and configured to receive, an amine absorbent stream containing heat stable amine salts and having a reduced concentration of CO 2 from the residual CO 2 removal unit, and operative for separating heat stable amine salts from said amine absorbent stream.
16 . A carbon dioxide (CO 2 ) capture system according to claim 15 , wherein the residual CO 2 removal unit is selected from the group consisting of a stripper, a flash drum and combinations thereof.
17 . A carbon dioxide (CO 2 ) capture system according to claim 16 , wherein the residual CO 2 removal unit comprises a stripper.
18 . A carbon dioxide (CO 2 ) capture system according to claim 16 , wherein the residual CO 2 removal unit comprises a flash drum.
19 . A carbon dioxide (CO 2 ) capture system according to claim 16 , wherein the residual CO 2 removal unit comprises a stripper and a flash drum arranged in series.
20 . A carbon dioxide (CO 2 ) capture system according to claim 15 , comprising:
a CO 2 absorber operative for scrubbing a gas stream comprising CO 2 with an amine absorbent such that a CO 2 rich amine absorbent is formed; and
a regenerator operative for regenerating CO 2 rich amine absorbent by heating it to separate CO 2 from the amine absorbent, such that a CO 2 lean amine absorbent is formed.
21 . A system according to claim 20 , wherein the residual CO 2 removal unit is in liquid connection with, and configured to receive, an amine absorbent stream from the regenerator, and operative for separating residual CO 2 from the CO 2 lean amine absorbent.
22 . A carbon dioxide (CO 2 ) capture system according to claim 15 , wherein the amine reclaimer is selected from the group consisting of an electrodialysis unit and an ion exchange unit.
23 . A carbon dioxide (CO 2 ) capture system according to claim 22 , wherein the amine reclaimer comprises an electrodialysis unit.
24 . A carbon dioxide (CO 2 ) capture system according to claim 22 , wherein the amine reclaimer comprises an ion exchange unit.
25 . A carbon dioxide (CO 2 ) capture system according to claim 15 , further comprising an amine absorbent cooler arranged between the residual CO 2 removal unit and the reclaimer and operative for cooling the amine absorbent from the residual CO 2 removal unit before it enters the reclaimer.
26 . A carbon dioxide (CO 2 ) capture system according to claim 25 , further comprising an indirect heat exchanger operative for subjecting the amine absorbent from the residual CO 2 removal unit to indirect heat exchange with the amine absorbent coming from the reclaimer.